Triple-Site Versus Standard Cardiac Resynchronization Therapy Study (TRUST CRT): Clinical Rationale, Design, and Implementation

Background: Cardiac resynchronization therapy (CRT) reduces morbidity and mortality in patients with heart failure (HF), lowered LV ejection fraction, and wide QRS. However, many patients (≤40%) do not respond to this form of pacing. TRUST CRT is a prospective, single-center, randomized, single-blind, parallel, and controlled study that has been designed to treat patients with moderate to severe HF (NYHA III-IV), QRS ≥120 ms, sinus rhythm, LV dysfunction (EF ≤ 35%), and signs of mechanical dyssynchrony.
Objective: The primary objective will evaluate the 6-month's combined endpoint of alive status, freedom from hospitalization for HF or heart transplantation, relative ≥10% increase in LV ejection fraction, ≥10% in peak oxygen consumption, and ≥10% in 6-minute walking distance.
Methods: Patients with HF receiving optimal pharmacotherapy, with LV dysfunction, mechanical dyssynchrony, wide QRS and sinus rhythm will be randomized in a 1: 1 fashion to standard or triple-site CRT-D. Patients will be followed for 1 week, 1, 3, and 6 months during a blind phase, then every 6 months until study completion. One hundred patients will be enrolled by the study center.
Conclusions: TRUST CRT is a randomized, clinical trial in CRT candidates to evaluate the effectiveness of triple-site pacing versus standard resynchronization in patients with HF.     

Serum Troponin I and Myoglobin After Monophasic versus Biphasic Transthoracic Shocks for Cardioversion of Persistent Atrial Fibrillation

This study compared the effects of standard monophasic versus biphasic direct current shocks for cardioversion of atrial fibrillation (AF) on the release of cardiac troponin I (cTnI) and myoglobin (Myo). We randomized 48 patients with persistent AF (mean age = 61.4 ± 10.7 years, 33 men) to monophasic (45.2%) or biphasic (54.8%) cardioversion. Plasma concentrations of cTn1 and Myo were measured before, and 6 and 24 hours after the procedure. Cardioversion was significantly more effective (88% vs 100%, P < 0.04) and required less energy (348.1 ± 254.1 vs 187.6 ± 105.3 J; P < 0.001) in the biphasic than the monophasic group. A significant increase in mean plasma cTnI concentration over 24 hours (0.23 ± 0.18 vs 0.41 ± 0.37 ng/mL, P < 0.04), and mean Myo concentration were recorded in the monophasic group over the first 6 hours following the procedure (38.2 ± 14.2 vs 221.9 ± 51.3 ng/mL, P < 0.001), whereas no significant increase was observed in the biphasic group. Increases in cTnI and Myo in the monophasic group correlated closely with the cumulative energy delivered (Spearman correlation coefficient r = 0.58, P = 0.004 for Myo and r = 0.67, P < 0.001 for cTnI). In addition, there was a positive correlation between cumulative cardioversion energy load and increase in Myo and cTnI indexed with left ventricular mass (r = 0.45, P < 0.02 for Myo and r = 0.47, P = 0.01 for cTnI). It is concluded that in cardioversion of AF, biphasic are more effective than monophasic and may cause less myocardial injury.     

The Monolithic Fetal Pacemaker:

DELL'ORFANO, J., et al .: The Monolithic Fetal Pacemaker: Prototype Lead Design for Closed Thorax Deployment. Prenatal sudden cardiac death and hydrops fetalis are often due to complete heart block. However, no pacing modality exists for intrauterine application for fetal bradycardia. A prototype lead for a novel fetal pacemaker has been developed and used in a direct pacing model. It has been demonstrated that the lead can be safely and successfully deployed using a hypochondriac and transdiaphragmatic or subxiphoid approach. Pacing with ventricular capture was evident with the widening of QRS duration from   50.2 ± 9.8   to   95.1 ± 12.8 ms (P = 0.0001)   . Further studies by echocardiogram revealed an increase in the pulse with pacing, confirming pacing. This study documents proof-of-concept for closed thorax over-the-wire deployment of a novel lead design applicable to fetal pacing. By combining the lead design with microcircuitry and a small power source, it is possible to create a monolithic fetal pacemaker system capable of being deployed in utero. (PACE 2003; 26[Pt. I]:805–811)     

Electrical Atrial Remodeling Assessed by Monophasic Action Potential and Atrial Refractoriness in Patients with Structural Heart Disease

The present study was performed to assess the effect of induced atrial fibrillation (AF) on atrial monophasic action potentials (MAPs) and atrial refractory period (ERP) in patients with structural heart disease. An electrode MAP catheter was placed in the right atrium to continuously measure atrial potential duration (APD₉₀) in 13 patients (coronary artery disease, 10 patients; dilated cardiomyopathy, 2 patients; hypertrophic cardiomyopathy, 1 patient) without spontaneous AF episodes. AF was induced by rapid atrial stimulation (300–1500/min). If sinus rhythm returned within 10 minutes, AF was reinduced. The atrial ERP was measured during atrial pacing at a basic cycle length of 550 ms before AF induction and after its conversion. Results: The mean atrial ERP and the atrial APD₉₀ before AF was 242 ± 34 ms and 256 ± 23 ms, respectively. ERP and APD_go shortening was observed after 3 minutes of AF. After 11 ± 0.5 min (10 min 20 s-13 min 10 s) of AF, ERP and APD₉₀ reached their minimal values of 72%± 13% and 71%± 10% of baseline, respectively. ERP and APD₉₀ returned to their initial values within 10 minutes after conversion of AF. A tendency toward longer duration of consecutive AF episodes and facilitation of their induction was observed. Conclusion: The present study confirms that short episodes of AF modify the electrophysiological properties of the atria in humans. In patients with structural heart disease, induced atrial fibrillation shortens the atrial ERP as well as the atrial APD₉₀. The changes were reversible within 10 minutes after arrhythmia termination.     

Electrocardiographic Diagnosis of Biventricular Pacing in Patients with Nonapical Right Ventricular Leads

Background: Assessment of left ventricular (LV) capture is of paramount importance in patients with biventricular (BiV) pacing. Our goal was to identify electrocardiographic features that differentiate between BiV and right ventricular (RV)‐only pacing in patients with nonapical RV leads. Methods: The study enrolled 300 consecutive patients with BiV devices and nonapical RV leads, and obtained from them 558 electrocardiograms with either BiV pacing (n = 300) or RV‐only pacing (n = 258). RV pacing served as a surrogate for loss of LV capture. Electrocardiograms from the first 150 patients were used to identify BiV‐specific features, and to construct an algorithm to differentiate between BiV and RV‐only pacing. Electrocardiograms from the second 150 patients were used to validate the algorithm. Results: The following electrocardiographic features typical of BiV pacing were identified: QS in lead V6 (specificity = 98.7%, sensitivity = 54.7%), dominant R in lead V1 (specificity = 100%, sensitivity = 23.3%), q in lead V6 (specificity = 96%, sensitivity = 22.7%), and a QRS < 160 ms (specificity = 100%, sensitivity = 66.0%). The algorithm based on those features was found to have an overall diagnostic accuracy of 95.0%, a specificity of 96.0%, and a sensitivity of 93.5%. Conclusions: The study identified QRS features that were very specific for BiV pacing in patients with nonapical RV leads. Sequential arrangement of those features resulted in an algorithm that was very accurate for differentiating between BiV pacing and loss of LV capture. (PACE 2012; 35:1199–1208)     

Immunopathologic and Histologic Studies on Skin from Pemphigus Patients in Tissue Culture

Explants of skin from patients with pemphigus vulgaris and pemphigus foliaceus taken in the active stages of the disease had in vivo bound IgG in the intercellular area. After 24-48 h incubation of these explants in normal sera acantholytic bullae developed above the stratum basale, thus indicating that the bound IgG is probably in vivo bound pemphigus antibody. In both cases, skin from the inactive stage of the disease contained no in vivo bound pemphigus antibodies. Explants of these skin specimens failed to develop acantholysis in culture.